Hyponatremia in peritoneal dialysis : free water overload, hyperosmolarity or malnutrition ?

Abstract

Hyponatremia is one of the most common electrolyte abnormalities in clinical practice and is associated with higher morbidity and mortality. On dialysis, hyponatremia is also quite common: 6 to 29% of hemodialysis patients and 11 to 26% of peritoneal dialysis (PD) patients have a serum ≤ 135mmol / L.
Hyponatremia in PD has unique aspects that confer different clinical consequences and treatment needs compared to subjects with normal kidney function.
The specificities of PD are mainly related to an ultrafiltrate quality, both in terms of sodium extraction and free water transfer, different according to the osmotic agent used in the dialysate (crystalloid or colloid osmotic agent) and according to the characteristics of the peritoneal membrane (functionality of aquaporins, preservation of osmotic conductance to glucose ...).
In the short or medium term, loss of residual renal function is highly correlated with the appearance of hyponatremia.
Finally, undernutrition, a frequent situation in dialysis and often associated with hypokalemia, can also be a cause of hyponatremia.
The purpose of this article is to help understand the pathophysiology of hyponatremia in PD, which is of paramount importance to ensure appropriate treatment.